In U.S. Pat. No. 6,132,924, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner comprising mixing a colorant, a latex, and two coagulants, followed by aggregation and coalescence, and wherein one of the coagulants may be polyaluminum chloride.
In U.S. Pat. No. 6,268,102, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner comprising mixing a colorant, a latex, and two coagulants, followed by aggregation and coalescence, and wherein one of the coagulants is a polyaluminum sulfosilicate.
Illustrated in U.S. Pat. No. 5,994,020, the disclosure of which is totally incorporated herein by reference, are toner processes, and more specifically, a process for the preparation of toner comprising:
(i) preparing, or providing a colorant dispersion;
(ii) preparing, or providing a functionalized wax dispersion comprised of a functionalized wax contained in a dispersant mixture comprised of a nonionic surfactant, an ionic surfactant, or mixtures thereof;
(iii) shearing the resulting mixture of the functionalized wax dispersion (ii) and the colorant dispersion (i) with a latex or emulsion blend comprised of resin contained in a mixture of an anionic surfactant and a nonionic surfactant;
(iv) heating the resulting sheared blend of (iii) below about the glass transition temperature (Tg) of the resin particles;
(v) optionally adding additional anionic surfactant to the resulting aggregated suspension of (iv) to prevent, or minimize additional particle growth of the resulting electrostatically bound toner size aggregates during coalescence (iv);
(vi) heating the resulting mixture of (v) above about the Tg of the resin; and optionally,
(vii) separating the toner particles.
The appropriate components and processes of the above recited copending applications and patents may be selected for the processes of the present invention in embodiments thereof.
The present invention is generally directed to toner processes, and more specifically, to chemical processes which involve the aggregation and fusion of a resin containing latex, colorant like pigment, or dye, and additive particles into toner particles, and wherein aggregation can be primarily controlled by utilizing a coagulant of polyaluminum sulfosilicate (PASS), which silicate is commercially available, and is believed to be disclosed in U.S. Pat. Nos. 4,981,675; 5,069,893; 5,149,400; 5,296,213, the disclosures of which are totally incorporated herein by reference; and subsequently adding a cationic ionic surfactant as a second co-coagulant, such as SANIZOL B(trademark), that is a benzylalkonium chloride, and wherein there is preferably selected a latex comprised of, for example, submicron resin particles in the size range of, for example, about 0.1 to about 0.5 micron in volume average diameter, suspended in an aqueous phase of water, nonionic and anionic surfactants and optionally suspended in an anionic surfactant to which is added a colorant dispersion comprising, for example, submicron colorant particles in the size range of, for example, about 0.08 to about 0.5 micron in volume average diameter, anionic surfactant, or optionally a nonionic surfactant, or mixtures thereof, and optionally adding thereto a wax dispersion comprising, for example, submicron wax particles in the size range of about 0.1 to about 0.5 micron in volume average diameter suspended in an aqueous phase of water and an anionic surfactant, and wherein the resultant blend is preferably stirred and heated to a temperature below the resin Tg, resulting in aggregates to which is optionally added thereto a second latex, followed by adjusting the pH of the mixture with a base, and heating the mixture to a temperature above the resin Tg, followed by lowering the pH of the mixture with, for example, a metal salt to fuse the aggregates.
More specifically, the present invention is generally directed to the aggregation of latex, colorant and optionally a wax in the presence of polyaluminum sulfosilicate and optionally a coagulant, such as SANIZOL B(trademark), that is benzylalkonium chloride, and wherein the coalescence or fusion of the aggregates is accomplished by a reduction of the pH with an aqueous solution of, for example, aluminum sulfate, and wherein there are generated toner compositions with, for example, a volume average diameter of from about 1 micron to about 25 microns, and preferably from about 2 microns to about 12 microns, and a narrow particle size distribution of, for example, from about 1.10 to about 1.33, and preferably a size distribution in the range of 1.11 to 1.25, the size and size distribution being measured by a Coulter Counter, without the need to resort to conventional pulverization and classification methods. Furthermore, the present invention in embodiments enables minimum washing, for example about 2 to about 4 washings, to provide a suitable toner triboelectrical charge, such as greater than about 20 xcexcC/g at 20 percent RH. The toners generated can be selected for known electrophotographic imaging and printing processes, including digital color processes.
In the embodiments of the present invention when a co-coagulant, such as SANIZOL B(trademark), is used in conjunction with the polyaluminum sulfosilicate (PASS), the process time may be further reduced by about 30 to about 50 percent as compared, for example, to similar toner processes wherein there is selected polyaluminum sulfosilicate alone. Furthermore, the advantage of using a second coagulant, such as SANIZOL B(trademark), in combination with PASS over polyaluminum chloride (PAC) alone resides in better retention of colorant wherein the colorant is, for example, about 95 to 100 percent retained in the toner particles. Additionally, with the invention processes in embodiments, toner washing can be reduced by about 60 to about 75 percent and the triboelectric charging values of the toner obtained are substantially constant irrespective of the colorant selected. Furthermore, when the toners generated are roll milled and aged over a period of, for example, about 2 to about 3 hours, there results stable and negative toner charging with, for example, no or minimal wrong sign positively charged toner.
The toners generated with the processes of the present invention are especially useful for imaging processes, especially xerographic processes, which usually prefer a toner transfer efficiency in excess of greater than about 90 percent, such as those with a compact machine design without a cleaner or those that are designed to provide high quality colored images with excellent image resolution, acceptable signal-to-noise ratio, and image uniformity. Also, the toners obtained with the processes illustrated herein can be selected for digital imaging systems and processes.
With respect to the prior art, only a small part thereof has been selected and this part may or may not be fully representative of the prior art teachings or disclosures.
In xerographic systems, especially color systems, small sized toners of from about 2 to about 8 microns can be of value with regard to the achievement of high image quality for process color applications. Also, of value is the achievement of a low image pile height to eliminate, or minimize image feel and avoid paper curling after fusing. Paper curling can be particularly pronounced in xerographic color processes primarily because of the presence of relatively high toner coverage as a result of the application of three to four colored toners. During fusing, moisture escapes from the paper due to high fusing temperatures of from about 120xc2x0 C. to about 200xc2x0 C., and wherein with only one layer of toner selected, such as in one-color black or highlight color xerographic applications, the amount of moisture driven off during fusing can be reabsorbed by the paper and the resulting print remains relatively flat with minimal paper curl. In process color where toner coverage is high, the relatively thick toner plastic covering on the paper can inhibit the paper from reabsorbing the moisture, and cause substantial paper curling. These and other imaging shortfalls and problems are avoided or minimized with the toners and processes of the present invention.
Also, it can be preferable to select certain toner particle sizes, such as from about 2 to about 10 microns, and with a high colorant, especially pigment loading, such as from about 4 to about 15 percent by weight of toner, so that the mass of toner necessary for attaining the required optical density and color gamut can be significantly reduced to eliminate or minimize paper curl. Lower toner mass also ensures the achievement of image uniformity. However, higher pigment loadings often adversely affect the charging behavior of toners. For example, the charge levels may be too low for proper toner development or the charge distributions may be too wide and toners of wrong charge polarity may be present. Furthermore, higher pigment loadings may also result in the sensitivity of charging behavior to charges in environmental conditions such as temperature and humidity. Toners prepared in accordance with the processes of the present invention minimize, or avoid these disadvantages.
There is illustrated in U.S. Pat. No. 4,996,127 a toner of associated particles of secondary particles comprising primary particles of a polymer having acidic or basic polar groups and a coloring agent. The polymers selected for the toners of the ""127 patent can be prepared by an emulsion polymerization method, see for example columns 4 and 5 of this patent. In column 7 of this ""127 patent, it is indicated that the toner can be prepared by mixing the required amount of coloring agent and optional charge additive with an emulsion of the polymer having an acidic or basic polar group obtained by emulsion polymerization. In U.S. Pat. No. 4,983,488, there is disclosed a process for the preparation of toners by the polymerization of a polymerizable monomer dispersed by emulsification in the presence of a colorant and/or a magnetic powder to prepare a principal resin component and then effecting coagulation of the resulting polymerization liquid in such a manner that the particles in the liquid after coagulation have diameters suitable for a toner. It is indicated in column 9 of this patent that coagulated particles of 1 to 100, and particularly 3 to 70 microns, are obtained. This process results, it is believed, in the formation of particles with a wide particle size distribution. Similarly, the aforementioned disadvantages, for example poor particle size distributions are obtained hence classification is required resulting in low toner yields, are illustrated in other prior art, such as U.S. Pat. No. 4,797,339, wherein there is disclosed a process for the preparation of toners by resin emulsion polymerization, wherein similar to the ""127 patent certain polar resins are selected; and U.S. Pat. No. 4,558,108, wherein there is disclosed a process for the preparation of a copolymer of styrene and butadiene by specific suspension polymerization. Other prior art includes U.S. Pat. Nos. 3,674,736; 4,137,188 and 5,066,560.
Emulsion/aggregation/coalescence processes for the preparation of toners are illustrated in a number of Xerox patents, the disclosures of each of which are totally incorporated herein by reference, such as U.S. Pat. No. 5,290,654, U.S. Pat. No. 5,278,020, U.S. Pat. No. 5,308,734, U.S. Pat. No. 5,370,963, U.S. Pat. No. 5,344,738, U.S. Pat. No. 5,403,693, U.S. Pat. No. 5,418,108, U.S. Pat. No. 5,364,729, and U.S. Pat. No. 5,346,797; and also of interest may be U.S. Pat. Nos. 5,348,832; 5,405,728; 5,366,841; 5,496,676; 5,527,658; 5,585,215; 5,650,255; 5,650,256 and 5,501,935, 5,723,253, 5,744,520, 5,763,133, 5,766,818, 5,747,215, 5,827,633, 5,853,944, 5,804,349, 5,840,462, 5,869,215. The appropriate components and processes of the above Xerox Corporation patents can be selected for the processes of the present invention in embodiments thereof.
It is a feature of the present invention to provide toner processes with many of the advantages illustrated herein.
In another feature of the present invention there are provided simple and economical processes for the preparation of black and colored toner compositions with excellent colorant dispersions, thus enabling the achievement of excellent color print quality.
In another feature of the present invention there is provided a process for preparing toner particles which evidence similar charging behavior despite differential colorant chemistry.
Another feature of the present invention resides in a process for preparing pigmented toner particles with certain coagulants, and wherein the toner is spherical in shape allowing, for example, excellent toner transfer as compared to rough or nonspherical toner.
Yet another feature of the present invention resides in a process of preparing different toner size particles with two coagulants, and wherein minimum amounts of ionic surfactant may be selected.
Additionally, another feature of the present invention resides in a process capable of delivering differing toner morphology particles such as spherical.
A further feature of the present invention resides in the use of a metal salt for the reduction of the pH during coalescence, rather than an acid for the fusion of the aggregates, wherein the use of the metal salts during the pH reduction stage enables rapid spheroidization of the particles when compared to the use of an acid, such as nitric acid, as a pH reducer.
Aspects of the present invention relate to a process comprising
(i) blending a colorant dispersion of a colorant, water, and an anionic surfactant, or a nonionic surfactant with
(ii) a latex emulsion comprised of resin, water, and an ionic surfactant;
(iii) adding to the resulting blend a first coagulant of polyaluminum sulfosilicate (PASS) and a second cationic co-coagulant having an opposite charge polarity to that of the latex surfactant;
(iv) heating the resulting mixture below about the glass transition temperature (Tg) of the latex resin;
(v) adjusting with a base the pH of the resulting toner aggregate mixture from a pH which is in the range of about 1.8 to about 3 to a pH range of about 5 to about 9;
(vi) heating above about the Tg of the latex resin;
(vii) changing the pH of the mixture by the addition of a metal salt to arrive at a pH of from about 2.8 to about 5; and
(viii) optionally isolating the product; a process comprising
(i) blending a colorant dispersion of a colorant, water, and an anionic surfactant, a latex emulsion comprised of resin, water, and an ionic surfactant; and optionally adding a crosslinked gel in the form of a latex, which latex is comprised of a crosslinked resin, water, and an ionic surfactant;
(ii) optionally adding a wax dispersion comprised of submicron wax particles in the size diameter of about 0.1 to about 0.4 micron, and which particles are dispersed in an anionic surfactant of the same charge polarity of the anionic surfactant in the latex emulsion;
(iii) adding to the resulting blend mixture polyaluminum sulfosilicate (PASS) and a cationic co-coagulant with an opposite charge polarity to that of the latex surfactant to thereby initiate flocculation of the latex resin, colorant and, when present, wax;
(iv) heating the resulting mixture below or equal to about the glass transition temperature (Tg) of the latex resin to form toner sized aggregates;
(v) optionally adding a second latex comprised of submicron resin particles suspended in an aqueous phase resulting in an aggregate shell;
(vi) adjusting the pH with a base of from a pH which is in the range of about 1.9 to about 3 to a pH range of about 5 to about 9 to primarily stabilize the aggregates;
(vii) heating the resulting aggregate suspension of (vi) above about the Tg of the latex resin;
(viii) retaining the mixture (vii) at an optional temperature in the range of from about 70xc2x0 C. to about 95xc2x0 C. to initiate the fusion or coalescence of the toner aggregates;
(ix) changing the pH of the above (viii) mixture by the addition of a metal salt to arrive at a pH in the range of about 2.8 to about 5 to thereby accelerate the fusion or the coalescence resulting in toner comprised of resin and colorant, wherein the toner particle size is from about 2 to about 25 microns in volume average diameter;
(x) optionally washing the resulting toner slurry; and optionally isolating the toner; a process for the preparation of toner comprising
(i) mixing a colorant dispersion of colorant, and an anionic surfactant with a latex emulsion comprised of resin, and an anionic surfactant;
(ii) adding to the resulting blend a first coagulant of polyaluminum sulfosilicate and a second cationic co-coagulant with an opposite charge polarity to that of the latex surfactant;
(iii) heating the resulting mixture below about the glass transition temperature (Tg) of the latex resin;
(iv) optionally adding a second latex comprised of submicron resin particles suspended in an aqueous phase resulting in a coating wherein the coating is optionally of from about 0.1 to about 1 micron in thickness;
(v) adjusting with a base the pH of the resulting mixture from a pH which is in the range of about 1.8 to about 3 to a pH range of about 5 to about 9;
(vi) heating the resulting aggregate suspension of (v) above about the Tg of the latex resin (i);
(vii) changing the pH of the (vi) mixture by the addition of a metal salt to arrive at a pH of from about 2.5 to about 5; optionally heating above the Tg of the resin latex; and isolating the toner; a toner process utilizing an aqueous metal salt solution as a pH reducer to enable spheroidization of toner aggregates that otherwise may not be spheroidizable with the use of normal known pH reducers, such as acids; and wherein the metal salt can also be selected as a pH reducer during coalescence, and wherein the latex resin selected possesses a high molecular weight, for example from about 60,000 to about 1,000,000, and more specifically, from about 70,000 to about 700,000 and an onset glass transition temperature of about 58xc2x0 C. to about 85xc2x0 C., and more specifically, about 60xc2x0 C. to about 75xc2x0 C.; a process for the preparation of toner compositions, with a volume average diameter of from about 1 to about 25 microns, and more specifically, from about 2 to about 12 microns, and a particle size distribution of about 1.10 to about 1.28, and more specifically, from about 1.15 to about 1.25, each as measured by a Coulter Counter without the need to resort to conventional classifications to narrow the toner particle size distribution; a process for the preparation of pigmented toner particles wherein the latex selected can be prepared by batch polymerization or a semi-batch polymerization process containing submicron resin particles suspended in an aqueous phase of surfactants followed by aggregation in the presence of a dual coagulant comprised of polyaluminum sulfosilicate and a cationic surfactant, such as SANIZOL B(trademark), that is a benzylalkonium chloride; a toner process wherein there are provided toner compositions with low fusing temperatures of from about 140xc2x0 C. to about 185xc2x0 C., and which toner compositions exhibit excellent blocking characteristics at and above about, or equal to about 45xc2x0 C., and which toners generate excellent developed print quality and high resolution color prints; and an emulsion/aggregation toner process providing toner compositions which enable high image projection efficiency, such as for example over 75 percent as measured by the Match Scan II spectrophotometer available from Million-Roy; a process for the preparation of toner comprising mixing a colorant, a latex, a wax and a polyaluminum sulfosilicate or a polyaluminum chloride and a second co-coagulant of, for example, benzylalkonium chloride, alkylbenzyl methyl ammonium chloride, or dialkylbenzenealkyl ammonium chloride; a process for the preparation of toner comprising mixing a colorant, a latex, a wax, and a polyaluminum sulfosilicate and a benzylalkonium chloride as coagulants, and which coagulants assist in permitting aggregation and coalescence of colorant, resin latex, and when present wax; a process for preparing a chemical toner comprising
(i) generating a colorant dispersion of a colorant, water, an ionic surfactant, or a nonionic surfactant; a latex emulsion comprised of resin, water, nonionic and ionic surfactant; and wherein the
(ii) colorant dispersion is blended with the latex emulsion followed by optionally adding a wax dispersion comprised of submicron particles in the diameter size range of about 0.1 to about 0.5 micron dispersed in an anionic surfactant of the same charge polarity as that of the ionic surfactant in the latex emulsion;
(iii) adding to the resulting blend containing the latex and colorant a coagulant of polyaluminum sulfosilicate (PASS) and a second cationic co-coagulant with an opposite charge polarity to that of the latex surfactant to thereby initiate flocculation of the resin latex and colorant particles;
(iv) heating the resulting mixture below about the glass transition temperature (Tg) of the latex resin to form toner sized aggregates of resin and colorant;
(v) optionally adding a second latex comprised of submicron resin particles suspended in an aqueous phase to the formed toner aggregates of (iv) resulting in a shell wherein the shell is, for example, of from about 0.1 to about 1 micron in thickness;
(vi) adjusting with a base the pH of the resulting toner aggregate mixture from a pH of about 1.9 to about 3 to a pH of about 5 to about 8 to primarily stabilize the aggregate particles;
(vii) heating the resulting aggregate suspension of (vi) above the Tg of the latex resin;
(viii) retaining the mixture (vii) at a temperature in the range of from about 70xc2x0 C. to about 95xc2x0 C. for a period of, for example, about 3 to about 10 hours to initiate the fusion or coalescence of the toner aggregates;
(ix) changing the pH of the above (viii) mixture with a metal salt to arrive at a pH in the range of about 2.8 to about 5, and more specifically, about 3 to about 4.5 to accelerate the fusion or the coalescence resulting in toner particles comprised of resin, colorant, and optionally wax, wherein the toner particle size is about 2 about 25 microns;
(x) washing the resulting toner slurry; and
(xi) isolating the toner; followed by drying the toner particles; a process comprising
(i) mixing a colorant dispersion of a colorant, water, an anionic surfactant with a latex comprised of resin, water, and an ionic surfactant followed by adding a crosslinked gel in the form of a latex and comprised of resin, water, and an ionic surfactant, and wherein the
(ii) colorant dispersion is thoroughly blended with the latex emulsion followed by adding a wax dispersion comprised of submicron particles in the size range of about 0.1 to about 0.5 micron dispersed in an anionic surfactant of the same charge polarity as that of the ionic surfactant in the latex emulsion;
(iii) adding to the resulting blend containing the latex and colorant a coagulant of polyaluminum sulfosilicate (PASS) and a second cationic co-coagulant of benzylalkonium chloride having an opposite charge polarity to that of the surfactant latex to thereby initiate flocculation of the resin latex and colorant particles;
(iv) heating the resulting mixture about below or about equal to the glass transition temperature (Tg) of the latex resin to form toner sized aggregates;
(v) optionally adding a second latex comprised of submicron resin particles suspended in an aqueous phase resulting in a shell wherein the shell is, for example, of from about 0.1 to about 1 micron in thickness;
(vi) adjusting with a base the pH of the resulting toner aggregate mixture to about 5 to about 9 to primarily stabilize the aggregate particles;
(vii) heating the resulting aggregate suspension of (vi) above the Tg of the latex resin;
(viii) retaining the mixture (vii) temperature of, for example, from about 70xc2x0 C. to about 95xc2x0 C. to initiate the fusion or coalescence of the toner aggregates;
(ix) changing the pH of the above (viii) mixture to arrive at a pH of about 2.8 to about 5, and more specifically, from about 3 to about 4.5 to accelerate the fusion or coalescence resulting in toner particles comprised of resin, colorant, and wax, wherein the toner particle size is about 2 to about 25 microns;
(x) washing the resulting toner slurry; and
(xi) isolating the toner; followed by drying the toner particles;
a process wherein a crosslinked gel is added to the latex, and which gel is comprised of styrene-beta carboxyl ethyl acrylate (xcex2CEA), divinyl benzene; a process wherein the amount of divinyl benzene crosslinking agent is from about 0.05 to about 5 percent by weight of resin; a process where the amount of the crosslinked gel latex is from about 5 to about 30 percent by weight of toner; a process wherein the crosslinked gel latex to the linear latex of (i) ratio is about 5:95 to about 30:70 percent by weight of the final toner formulation; a process wherein the final toner formulation is comprised of a linear resin and optionally a crosslinked gel resin and a colorant; a process wherein the polyaluminum sulfosilicate is selected in an amount of from about 0.05 to about 7 percent by weight of toner solids of latex resin, colorant, optional wax and sulfosilicate, and wherein the latex resin, colorant, and wax amount totals about 100 percent; a toner process wherein there is selected a second coagulant of a cationic surfactant; a process wherein the second coagulant selected is, for example, an alkonium benzalkonium chloride, dialkylbenzenealkyl ammonium chloride, alkylbenzyl methyl ammonium chloride or alkylbenzyl dimethyl ammonium bromide and the like in an amount of from about 0.05 to about 5 weight percent by weight; a process wherein the metal salt to reduce the pH of the mixture during the coalescence (vii) is selected, for example, from sulfates, chloride, nitrates, and acetates of aluminum, magnesium, zinc, and potassium; a process wherein the metal salt is aluminum sulfate, aluminum chloride, zinc sulfate, magnesium sulfate, magnesium chloride, potassium-aluminum sulfate, and the preferred metal salt is aluminum sulfate; a process wherein the concentration of the metal salt used to reduce the pH is from about 0.01 to about 10 percent, and more specifically, from about 0.05 to about 7 weight percent by weight of toner; a process wherein the base is a hydroxide selected from the group consisting of sodium hydroxide, potassium hydroxide, and ammonium hydroxide, and wherein a specific base is sodium hydroxide; a process wherein there is added to the formed toner aggregates a second latex comprised of resin particles suspended in an aqueous phase containing an ionic surfactant, and wherein the second latex is selected in an amount of about 10 to about 40 percent by weight of the initial latex and forms a shell or coating on the toner aggregates; a process wherein the added latex contains the same resin as the initial latex, or wherein the added latex contains a dissimilar resin than that of the initial latex; a process wherein the temperature at which the aggregation is accomplished controls the size of the aggregates, and wherein the final toner size is from about 2 to about 15 microns in volume average diameter; a process wherein the aggregation temperature is from about 45xc2x0 C. to about 60xc2x0 C., and wherein the coalescence or fusion temperature is from about 85xc2x0 C. to about 95xc2x0 C.; a process wherein the colorant is a pigment, and wherein the pigment is in the form of dispersion, and which dispersion contains an ionic surfactant, and wherein the polyaluminum sulfosilicate and the benzylalkonium chloride function as coagulants and enable aggregation of the latex wax and the colorant; a process wherein the coagulant is added during or prior to aggregation of the latex resin and colorant, and which coagulant enables or initiates the aggregation; a process wherein the colorant is carbon black, cyan, yellow, red, green, blue, magenta, or mixtures thereof; a process wherein the toner isolated is from about 2 to about 25 microns in volume average diameter, and the particle size distribution (GSD) thereof is from about 1.15 to about 1.30; and wherein there is added to the surface of the formed toner additives, such as metal salts, metal salts of fatty acids, silicas, metal oxides, or mixtures thereof, each in an amount of from about 0.1 to about 10 weight percent of the obtained toner; a process which comprises mixing a latex, surfactant and colorant; heating in the presence of a polyaluminum sulfosilicate and benzyl alkonium chloride (SANIZOL B(trademark)) the resulting mixture below about, or equal to about the glass transition temperature of the latex resin; followed by the addition of a base to stabilize the toner aggregates; thereafter heating the resulting aggregates above about, or about equal to the glass transition temperature of the resin; and isolating, washing and drying the toner; a process wherein prior to isolating the heating is retained at a temperature of from about 70xc2x0 C. to about 95xc2x0 C. until fusion or coalescence of the aggregates is accomplished; a process wherein the polyaluminum sulfosilicate possesses a weight average molecular weight of from about 5,000 to about 100,000; a process wherein the sulfosilicate functions as a coagulant and enables or assists in enablement of the aggregation; a process wherein the polyaluminum sulfosilicate is of the formula
ALA(OH)B(SO4)C(SIOX)D(H2O)E
where A, B, C, D and E represent the number of segments of each species, and X represents the number of oxygens; a process wherein A is 1, B is from about 0.75 to about 2, C is from about 0.30 to about 1.12, D is from about 0.005 to about 0.1, X is from about 2 to about 4, and E is from about 4 to about 10; a process wherein the aggregation temperature is from about 40xc2x0 C. to about 62xc2x0 C., and more specifically, is from about 45xc2x0 C. to about 58xc2x0 C.; a process wherein the coalescence temperature is from about 75xc2x0 C. to about 95xc2x0 C., and more specifically, about 85xc2x0 C. to about 90xc2x0 C.; a process wherein there is added to the aggregate mixture prior to coalescence a base component; a process wherein the base is an alkali metal hydroxide; a process wherein the hydroxide is sodium hydroxide; a process wherein the pH of the mixture resulting after aggregation is increased from about 2 to about 2.6 to about 7 to about 8 during the coalescence, and wherein the base functions primarily as a stabilizer for the toner aggregates during the coalescence; a process wherein the amount of base selected is from about 8 to about 25 weight percent, and more specifically, is from about 10 to about 20 weight percent; a process wherein the amount of metal hydroxide selected is from about 11 to about 14 weight percent; a process wherein the metal salt to reduce the pH is a sulfate, a chloride, a nitrate, or an acetate of aluminum, magnesium, zinc, and potassium; a process wherein the salt is aluminum sulfate, aluminum chloride, zinc sulfate, magnesium sulfate, magnesium chloride, potassium-aluminum sulfate, or zinc acetate, and which salt is selected in an amount of from about 0.05 to about 10 percent, and more specifically, in the amount of about 0.1 about 7 weight percent by weight of toner; a process wherein the latex contains submicron polymer or resin particles containing a polymer selected from the group consisting of poly(styrene-alkyl acrylate), poly(styrene-1,3-diene), poly(styrene-alkyl methacrylate), poly(styrene-alkyl acrylate-acrylic acid), poly(styrene-1,3-diene-acrylic acid), poly(styrene-alkyl methacrylate-acrylic acid), poly(alkyl methacrylate-alkyl acrylate), poly(alkyl methacrylate-aryl acrylate), poly(aryl methacrylate-alkyl acrylate), poly(alkyl methacrylate-acrylic acid), poly(styrene-alkyl acrylate-acrylonitrile-acrylic acid), poly(styrene-1,3-dieneacrylonitrile-acrylic acid), and poly(alkyl acrylate-acrylonitrile-acrylic acid); a process wherein the latex contains a resin selected from the group consisting of poly(styrene-butadiene), poly(methylstyrene-butadiene), poly(methyl methacrylate-butadiene), poly(ethyl methacrylate-butadiene), poly(propyl methacrylate-butadiene), poly(butyl methacrylate-butadiene), poly(methyl acrylate-butadiene), poly(ethyl acrylate-butadiene), poly(propyl acrylate-butadiene), poly(butyl acrylate-butadiene), poly(styrene-isoprene), poly(methylstyrene-isoprene), poly(methyl methacrylate-isoprene), poly(ethyl methacrylate-isoprene), poly(propyl methacrylate-isoprene), poly(butyl methacrylate-isoprene), poly(methyl acrylate-isoprene), poly(ethyl acrylate-isoprene), poly(propyl acrylate-isoprene), and poly(butyl acrylate-isoprene); poly(styrene-propyl acrylate), poly(styrene-butyl acrylate), poly(styrene-butadiene-acrylic acid), poly(styrene-butadiene-methacrylic acid), poly(styrene-butadiene-acrylonitrile-acrylic acid), poly(styrene-butyl acrylate-acrylic acid), poly(styrene-butyl acrylate-methacrylic acid), poly(styrene-butyl acrylate-acrylononitrile), and poly(styrene-butyl acrylate-acrylononitrile-acrylic acid); and wherein the colorant is a pigment; a process for the preparation of toner particles resulting in images with excellent print quality, and wherein there is selected a latex comprised of submicron resin particles which are in the size range of about 0.05 to about 0.5 micron, and more specifically, in the size range of about 0.07 to about 0.35 micron, suspended in an aqueous water phase containing an ionic surfactant, which is selected in an amount of about 0.5 to about 5 percent, and more specifically, about 0.7 to about 2 percent by weight of solids, to which is added a colorant dispersion comprising submicron, for example less than, or equal to about 0.5 micron, colorant particles, anionic or a nonionic surfactant which is selected in the amount of about 0.5 to about 10 percent, and more specifically, about 0.6 to about 5 percent by weight of solids, which when blended together result in a mixture with a pH of about 2 to about 2.6 to which a polyaluminum sulfosilicate (PASS) solution containing an acid like nitric acid is added slowly over, for example, a period of about 2 to about 5 minutes, followed by the addition of a cationic coagulant surfactant solution of SANIZOL B(trademark) in water wherein the amount of PASS is from about 0.05 to about 0.8 percent by weight of the latex solids and colorant components, and specifically, from about 0.06 to about 0.5 percent by weight; and the second optional coagulant, such as SANIZOL B(trademark), is selected in the amount of about 0.05 to about 0.8 percent by weight of solids, and more specifically, from about 0.06 to about 0.5 percent by weight; further aggregating by stirring and heating from about 5 to about 10 degrees below the resin Tg, resulting in toner aggregates of a size of about 3 to about 15 microns, and more specifically, about 4 to about 8 microns with a narrow GSD of, for example, about 1.14 to about 1.28, and more specifically, about 1.17 to about 1.25, and which improved GSD enables the clean transfer of the toner particles in xerographic systems thereby providing enhanced resolution of the fused images; followed by adjusting the pH of the mixture from about 2 to about 2.6 to a pH of about 6 to about 9, and more specifically, to about 7 to about 8.5, or to a pH of about 8 with the addition of a dilute base solution of 4 weight percent of sodium hydroxide to primarily stabilize the aggregates, further stirring and increasing the mixture temperature above the resin Tg, in the range of about 70xc2x0 C. to about 95xc2x0 C., and more specifically, from about 85xc2x0 C. to about 93xc2x0 C. for a period of about 0.5 to about 1.5 hours, followed by changing the pH from about 8 to about 4.5 by the use of an aqueous metal salt solution, such as a dilute solution of aluminum sulfate in water wherein the concentration of aluminum sulfate is from about 0.5 to about 5 weight percent, and more specifically, about 0.75 to about 3.5 weight percent, and heating the mixture for an additional about 0.5 to about 4 hours, and more specifically, from about 0.6 to about 3 hours, to fuse or coalesce the aggregates, and then washing and drying the toner; a toner process wherein a wax dispersion is added to the latex and colorant mixture; a process wherein the use of an aqueous solution of a metal salt to reduce the pH of step (ix) enables rapid spheroidization of the toner particles; and the rapid spheroidization with the use of a metal salt as a pH reducer enhances by about 2 to about 4 times faster than that when an acid is selected; and a process for the preparation of toner compositions which comprises blending an aqueous colorant dispersion containing a pigment, such as carbon black, phthalocyanine, quinacridone or RHODAMINE B(trademark) type, red, green, orange, brown, violet, yellow, fluorescent colorants and the like, with a latex emulsion derived from the emulsion polymerization of monomers selected, for example, from the group consisting of styrene, butadiene, acrylates, methacrylates, acrylonitrile, acrylic acid, methacrylic acid, itaconic or Beta Carboxy Ethyl Acrylate (xcex2CEA) and the like, and which latex contains an ionic surfactant, such as sodium dodecylbenzene sulfonate, and optionally a nonionic surfactant, and which process is accomplished in the presence of a metal salt, or PASS and a second coagulant cationic surfactant, heating the resulting flocculent mixture at a temperature below the resin Tg for an effective length of time of, for example, about 0.5 hour to about 3 hours to form toner sized aggregates; and optionally adding a known amount of delayed latex wherein the latex can be the same as the above initial latex or dissimilar, followed by adjusting the pH of the mixture with a dilute base solution of sodium hydroxide, and subsequently heating the aggregate suspension at a temperature at or below 95xc2x0 C. for a period of 0.5 to 1 hour, adjusting the pH of the mixture from about 8 to about 4.5 with an aqueous dilute metal salt of aluminum sulfate to provide spherical toner particles, isolating the toner product by, for example, filtration, washing and drying in an oven, fluid bed dryer, freeze dryer, or spray dryer.
The particle size of the toner provided by the processes of the present invention in embodiments can be controlled, for example, by the temperature at which the aggregation of latex, colorant, such as pigment, and optional additives is conducted. In general, the lower the aggregation temperature, the smaller the aggregate size, and thus the final toner size. For a latex polymer with a glass transition temperature (Tg) of about 55xc2x0 C. and a reaction mixture with a solids content of about 14 percent by weight, an aggregate size of about 7 microns in volume average diameter is obtained at an aggregation temperature of about 53xc2x0 C.; the same latex will provide an aggregate size of about 5 microns at a temperature of about 48xc2x0 C. under similar conditions.
Illustrative examples of specific latex resin, polymer or polymers selected for the process of the present invention include known polymers such as poly(styrene-butadiene), poly(methyl methacrylate-butadiene), poly(ethyl methacrylate-butadiene), poly(propyl methacrylate-butadiene), poly(butyl methacrylate-butadiene), poly(methyl acrylate-butadiene), poly(ethyl acrylate-butadiene), poly(propyl acrylate-butadiene), poly(butyl acrylate-butadiene), poly(styrene-isoprene), poly(methylstyrene-isoprene), poly(methyl methacrylate-isoprene), poly(ethyl methacrylate-isoprene), poly(propyl methacrylate-isoprene), poly(butyl methacrylate-isoprene), poly(methyl acrylate-isoprene), poly(ethyl acrylate-isoprene), poly(propyl acrylate-isoprene), poly(butyl acrylate-isoprene), poly(styrene-butylacrylate), poly(styrene-butadiene), poly(styrene-isoprene), poly(styrene-butyl methacrylate), poly(styrene-butyl acrylate-acrylic acid), poly(styrene-butadiene-acrylic acid), poly(styrene-isoprene-acrylic acid), poly(styrene-butyl methacrylate-acrylic acid), poly(butyl methacrylate-butyl acrylate), poly(butyl methacrylate-acrylic acid), poly(styrene-butyl acrylate-acrylonitrile-acrylic acid), poly(acrylonitrile-butyl acrylate-acrylic acid), and the like. The crosslinked gel latex when selected can contain divinyl benzene as an additional monomer during the latex formation. The latex polymer, or resin is generally present in the toner compositions of the present invention in various suitable amounts, such as from about 75 weight percent to about 98, or from about 80 to about 95 weight percent of the toner or of the solids, and the latex size suitable for the processes of the present invention can be, for example, more specifically, from about 0.05 micron to about 0.7 micron in volume average diameter as measured by the Brookhaven nanosize particle analyzer. Other sizes and effective amounts of latex polymer may be selected in embodiments. The total of all toner components, such as resin and colorant, is about 100 percent, or about 100 parts.
The polymer selected for the process of the present invention can be prepared by emulsion polymerization methods, and the monomers utilized in such processes include, for example, styrene, acrylates, methacrylates, butadiene, isoprene, acrylic acid, methacrylic acid, itaconic acid, beta carboxy ethyl acrylate, acrylonitrile, and the like. Known chain transfer agents, for example dodecanethiol, from, for example, about 0.1 to about 10 percent, or carbon tetrabromide in effective amounts, such as for example from about 0.1 to about 10 percent, can also be utilized to control the molecular weight properties of the polymer when emulsion polymerization is selected. Other processes of obtaining polymer particles of from, for example, about 0.01 micron to about 2 microns can be selected from polymer microsuspension process, such as disclosed in U.S. Pat. No. 3,674,736, the disclosure of which is totally incorporated herein by reference; polymer solution microsuspension process, such as disclosed in U.S. Pat. No. 5,290,654, the disclosure of which is totally incorporated herein by reference, mechanical grinding processes, or other known processes. Also, the reactant initiators, chain transfer agents, and the like as disclosed in U.S. Ser. No. 922,437, the disclosure of which is totally incorporated herein by reference, can be selected for the processes of the present invention.
Examples of waxes include those as illustrated herein, such as those disclosed in the aforementioned copending applications, polypropylenes and polyethylenes commercially available from Allied Chemical and Petrolite Corporation, wax emulsions available from Michaelman Inc. and the Daniels Products Company, EPOLENE N-15 commercially available from Eastman Chemical Products, Inc., VISCOL 550-P, a low weight average molecular weight polypropylene available from Sanyo Kasei K.K., and similar materials. The commercially available polyethylenes selected have, it is believed, a molecular weight Mw of from about 1,000 to about 1,500, while the commercially available polypropylenes are believed to have a molecular weight of from about 4,000 to about 5,000. Examples of functionalized waxes include, amines, amides, for example aqua SUPERSLIP 6550, SUPERSLIP 6530 available from Micro Powder Inc., fluorinated waxes, for example POLYFLUO 190, POLYFLUO 200, POLYFLUO 523XF, AQUA POLYFLUO 411, AQUA POLYSILK 19, POLYSILK 14 available from Micro Powder Inc., mixed fluorinated, amide waxes, for example MICROSPERSION 19 also available from Micro Powder Inc., imides, esters, quaternary amines, carboxylic acids or acrylic polymer emulsion, for example JONCRYL 74, 89, 130, 537, and 538, all available from SC Johnson Wax, chlorinated polypropylenes and polyethylenes commercially available from Allied Chemical and Petrolite Corporation and SC Johnson wax.
Various known colorants, such as pigments, selected for the processes of the present invention and present in the toner in an effective amount of, for example, from about 1 to about 25 percent by weight of toner, and preferably in an amount of from about 3 to about 10 percent by weight, that can be selected include, for example, carbon black like REGAL 330(copyright); magnetites, such as Mobay magnetites MO8029(trademark), MO8060(trademark); Columbian magnetites; MAPICO BLACKS(trademark) and surface treated magnetites; Pfizer magnetites CB4799(trademark), CB5300(trademark), CB5600(trademark), MCX6369(trademark); Bayer magnetites, BAYFERROX 8600(trademark), 8610(trademark); Northern Pigments magnetites, NP-604(trademark), NP-608(trademark); Magnox magnetites TMB-100(trademark), or TMB-104(trademark); and the like. As colored pigments, there can be selected cyan, magenta, yellow, red, green, brown, blue or mixtures thereof. Specific examples of pigments include phthalocyanine HELIOGEN BLUE L6900(trademark), D6840(trademark), D7080(trademark), D7020(trademark), PYLAM OIL BLUE(trademark), PYLAM OIL YELLOW(trademark), PIGMENT BLUE 1(trademark) available from Paul Uhlich and Company, Inc., PIGMENT VIOLET 1(trademark), PIGMENT RED 48(trademark), LEMON CHROME YELLOW DCC 1026(trademark), E.D. TOLUIDINE RED(trademark) and BON RED C(trademark) available from Dominion Color Corporation, Ltd., Toronto, Ontario, NOVAPERM YELLOW FGL(trademark), HOSTAPERM PINK E(trademark) from Hoechst, and CINQUASIA MAGENTA(trademark) available from E.l. DuPont de Nemours and Company, and the like. Generally, colored pigments that can be selected are cyan, magenta, or yellow pigments, and mixtures thereof. Examples of magentas that may be selected include, for example, 2,9-dimethyl-substituted quinacridone and anthraquinone dye identified in the Color Index as CI 60710, CI Dispersed Red 15, diazo dye identified in the Color Index as CI 26050, CI Solvent Red 19, and the like. Illustrative examples of cyans that may be selected include copper tetra(octadecyl sulfonamido) phthalocyanine, x-copper phthalocyanine pigment listed in the Color Index as CI 74160, CI Pigment Blue, and Anthrathrene Blue, identified in the Color Index as CI 69810, Special Blue X-2137, and the like; while illustrative examples of yellows that may be selected are diarylide yellow 3,3-dichlorobenzidene acetoacetanilides, a monoazo pigment identified in the Color Index as CI 12700, CI Solvent Yellow 16, a nitrophenyl amine sulfonamide identified in the Color Index as Foron Yellow SE/GLN, CI Dispersed Yellow 33 2,5-dimethoxy-4-sulfonanilide phenylazo-4xe2x80x2-chloro-2,5-dimethoxy acetoacetanilide, Yellow 180 and Permanent Yellow FGL. Colored magnetites, such as mixtures of MAPICO BLACK(trademark), and cyan components may also be selected as pigments for the processes of the present invention, wherein the pigment amount is in the range of 3 to 15 weight percent of the toner. Dye examples include known suitable dyes, reference the Color Index, and a number of U.S. patents, such as food dyes, and the like.
Colorants include pigment, dye, mixtures of pigment and dyes, mixtures of pigments, mixtures of dyes, and the like.
Examples of initiators for the latex preparation include water soluble initiators, such as ammonium and potassium persulfates, in suitable amounts, such as from about 0.1 to about 8 percent, and more specifically, from about 0.2 to about 5 percent (weight percent). Examples of organic soluble initiators include VAZO peroxides, such as VAZO 64, 2-methyl 2-2xe2x80x2-azobis propanenitrile, VAZO 88, 2-2xe2x80x2-azobis isobutyramide dehydrate in a suitable amount, such as from about 0.1 to about 8 percent. Examples of chain transfer agents include dodecane thiol, octane thiol, carbon tetrabromide and the like in various suitable amounts, such as from about 0.1 to about 10 percent, and more specifically, from about 0.2 to about 5 percent by weight of monomer.
Surfactants for the preparation of the latexes and the colorant dispersions can be ionic or nonionic surfactants, in effective amounts of, for example, from about 0.01 to about 15, or from about 0.01 to about 5 weight percent of the reaction mixture. Anionic surfactants include sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate, sodium dodecyinaphthalene sulfate, dialkyl benzenealkyl, sulfates and sulfonates, abitic acid, available from Aldrich, NEOGEN R(trademark), NEOGEN SC(trademark) obtained from Kao, and the like. Examples of cationic surfactants are dialkyl benzenealkyl ammonium chloride, lauryl trimethyl ammonium chloride, alkylbenzyl methyl ammonium chloride, alkyl benzyl dimethyl ammonium bromide, benzalkonium chloride, cetyl pyridinium bromide, C12, C15, C17 trimethyl ammonium bromides, halide salts of quaternized polyoxyethylalkylamines, dodecylbenzyl triethyl ammonium chloride, MIRAPOL(trademark) and ALKAQUAT(trademark) available from Alkaril Chemical Company, SANIZOL(trademark) (benzalkonium chloride) available from Kao Chemicals, and the like, selected in effective amounts of, for example, from about 0.01 percent to about 10 percent by weight. The molar ratio of the cationic surfactant used for flocculation to the anionic surfactant used in the latex preparation is, for example, from about 0.5 to about 4.
Examples of nonionic surfactants selected in various suitable amounts, such as about 0.1 to about 5 weight percent, are polyvinyl alcohol, polyacrylic acid, methalose, methyl cellulose, ethyl cellulose, propyl cellulose, hydroxy ethyl cellulose, carboxy methyl cellulose, polyoxyethylene cetyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether, dialkylphenoxy poly(ethyleneoxy) thanol, available from Rhone-Poulenac as IGEPAL CA-210(trademark), IGEPAL CA-520(trademark), IGEPAL CA-720(trademark), IGEPAL CO-890(trademark), IGEPAL CO-720(trademark), IGEPAL CO-290(trademark), IGEPAL CA-210(trademark), ANTAROX 890(trademark) and ANTAROX 897(trademark), can be selected.
Examples of the first coagulant are polyaluminum sulfosilicates, which, for example, can be represented by the formula
ALA(OH)B(SO4)C(SIOX)D(H2O)E
wherein
A is the number of Al segments and can be a number of about 1 to about 2;
B is a number of from about 0.75 to about 2;
C is from about 0.30 to about 1.12;
D is from about 0.005 to about 0.1;
X is a number equal to or greater than 2 but less than or equal to about 4 wherein 3=B+2C+2D (X-2); and
E is a number of larger than about 4, such as from about 5 to about 10, or more generally, wherein A, B, C, D, X and E represent the number of segments or atoms with respect to X, which represents the number of oxygen atoms.
Examples of the second surfactant coagulant are dialkyl benzenealkyl ammonium chloride, lauryl trimethyl ammonium chloride, alkylbenzyl methyl ammonium chloride, alkyl benzyl dimethyl ammonium bromide, and the like, and wherein alkyl contains, for example, from about 5 to about 20 carbon atoms, with the amounts of each of the first and second coagulant being from about 0.03 percent to about 1 percent by weight of toner aggregates, and more specifically, from about 0.05 to about 0.5 percent by weight of toner aggregates.
Examples of metal salts used as a pH reducer for (ix) can be selected from, for example, halides like chlorides, sulfates, nitrates, and acetates of aluminum, magnesium, zinc, and potassium, and more specifically, wherein the salt is aluminum sulfate, aluminum chloride, zinc sulfate, magnesium sulfate, magnesium chloride, or potassium-aluminum sulfate, or water soluble metal salts, that is metal salts that are readily soluble in water.
The toner may also include known charge additives in effective suitable amounts of, for example, from 0.1 to 5 weight percent, such as alkyl pyridinium halides, bisulfates, the charge control additives of U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014; 4,394,430 and 4,560,635, the disclosures of which are totally incorporated herein by reference, negative charge enhancing additives like aluminum complexes, other known charge additives, and the like.
Surface additives that can be added to the toner compositions after washing or drying include, for example, metal salts, metal salts of fatty acids, colloidal silicas, metal oxides, strontium titanates, mixtures thereof, and the like, which additives are each usually present in an amount of from about 0.1 to about 2 weight percent, reference for example U.S. Pat. Nos. 3,590,000; 3,720,617; 3,655,374 and 3,983,045, the disclosures of which are totally incorporated herein by reference. Specific additives include zinc stearate and AEROSIL R972(copyright) available from Degussa. The coated silicas of U.S. Pat. No. 6,190,815 and U.S. Pat. No. 6,004,714, the disclosures of which are totally incorporated herein by reference, can also be selected in amounts, for example, of from about 0.1 to about 2 percent, which additives can be added during the aggregation or blended into the formed toner product.
Developer compositions can be prepared by mixing the toners obtained with the processes of the present invention, from about 2 percent toner concentration to about 8 percent toner concentration, with known carrier particles, including coated carriers, such as steel, ferrites, and the like, reference U.S. Pat. Nos. 4,937,166 and 4,935,326, the disclosures of which are totally incorporated herein by reference. The carrier particles can also be comprised of a core with a polymer coating thereover, such as polymethylmethacrylate (PMMA) having dispersed therein a conductive component like conductive carbon black. Carrier coatings include silicone resins, fluoropolymers, mixtures of resins not in close proximity in the triboelectric series, thermosetting resins, and other known components.
Imaging methods are also envisioned with the toners of the present invention, reference for example a number of the patents mentioned herein, and U.S. Pat. Nos. 4,265,990; 4,858,884; 4,584,253 and 4,563,408, the disclosures of which are totally incorporated herein by reference.